This invention relates to the field of polyethylene compositions.
Ultraviolet light has a wave length from about 10 to about 400 nanometers. When ultraviolet radiation comes into contact with a polymer, that polymer tends to degrade into a less useful composition.
Recently however, ultraviolet light radiation has been used to cure labels onto plastic articles as well as to cure certain types of printing inks onto plastic articles. The advantages of using ultraviolet light radiation to cure printing ink is that these UV curable printing inks containing very little solvent in them. This promotes fast curing of the printing ink as well as elimination of any fire hazard associated with using a solvent-based liquid ink.
Another advantage of using ultraviolet light radiation is the elimination of the thermal ovens that are usually used in drying solvent based liquid inks. This produces a cost savings as well as an energy savings by not using these thermal ovens. Additionally, due to recent clean air legislation the use of solvent based liquid inks is undesirable since 30 to 60% of a solvent-based liquid ink evaporates into the air.
However, it was recently discovered that while subjecting certain types of polyethylene compositions to high intensity ultraviolet light radiation these compositions discolored. This invention provides a solution to minimize this discoloring phenomenon.